The subject invention is directed toward the fluid coupling art and, more particularly, to an improved tube coupling particularly suited for use in high vacuum and pressure systems.
One type of coupling which has achieved widespread acceptance comprises a pair of coupling components having longitudinally extending fluid passageways and terminating in mating end faces each constituting a sealing face with an annular rib or sealing bead which extends outwardly about the associated end. With the components oriented with end faced in face-to-face relationship, an annular metal sealing gasket is interposed between the sealing beads. Suitable threaded nuts act to drive the coupling components together to cause the annular ribs to sealingly engage the gasket.
In order to properly locate the sealing gasket relative to the end faces, various gasket retainers have been proposed in the prior art. These retainers are shown, for example, in U.S. Pat. Nos. 4,552,389; 4,650,227; and, 4,838,583. The gasket retainers have been very satisfactory for their intended purpose. Recently, however, a modified form of the basic coupling design has presented difficulties with respect to the prior gasket retainers.
To understand the above, reference should be had to the commonly assigned co-pending application, Ser. No. 468,691, now U.S. Pat. No. 5,066,051, filed Jan. 23, 1990, and titled "Anti-Twist Coupling Assembly" which is incorporated herein by reference. In this new coupling design, a separate anti-torque member is mounted inside the nut members in surrounding relationship with the ends of the sealing face. This anti-torque member acts to prevent transmission of torque to the coupling components, the sealing washer, or the associated piping during tightening of the nut members.
The presence of the anti-torque member can have the effect of increasing the overall external dimensions of the coupling. In an effort at keeping these external dimensions small, the spacings between the components is reduced as much as possible. As a consequence, it is somewhat difficult to use the more conventional gasket retaining devices. Further, with the conventional gasket retainer, it is necessary for the gasket to have a smaller outer diameter than the gasket required when a retainer is not used. Thus, two different gaskets must be stocked.